B4.23 ICH_VTR, Interrupt Controller VGIC Type Register

ICH_VTR reports supported GIC virtualization features.

Bit field descriptions

ICH_VTR is a 32-bit register and is part of:

  • The GIC system registers functional group.
  • The Virtualization registers functional group.
  • The GIC host interface control registers functional group.
Figure B4-13 ICH_VTR bit assignments
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PRIbits, [31:29]

Priority bits. The number of virtual priority bits implemented, minus one.


Priority implemented is 5-bit.

PREbits, [28:26]

The number of virtual preemption bits implemented, minus one. The value is:


Virtual preemption implemented is 5-bit.

IDbits, [25:23]

The number of virtual interrupt identifier bits supported. The value is:


Virtual interrupt identifier bits implemented is 16-bit.

SEIS, [22]

SEI Support. The value is:


The virtual CPU interface logic does not support generation of SEIs.

A3V, [21]

Affinity 3 Valid. The value is:


The virtual CPU interface logic supports non-zero values of Affinity 3 in SGI generation System registers.

nV4, [20]

Direct injection of virtual interrupts not supported. The value is:


The CPU interface logic supports direct injection of virtual interrupts.

TDS, [19]

Separate trapping of Non-secure EL1 writes to ICV_DIR supported. The value is:


Implementation supports ICH_HCR.TDIR.

RES0, [18:5]

Reserved, RES0.

ListRegs, [4:0]

The number of implemented List registers, minus one. The value is:

3The core implements four List registers.

AArch32 System register ICH_VTR is architecturally mapped to AArch64 System register ICH_VTR_EL2.

If EL2 is not implemented, all bits in this register are RES0 from EL3, except for nV4, which is RES1 from EL3.

Bit fields and details not provided in this description are architecturally defined. See the Arm® Generic Interrupt Controller Architecture Specification.

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